here - Australian College of Veterinary Scientists

anecdotal success with use of human dust mite-proof bedding covers, for example
using a dust mite-proof mattress cover or duvet cover next to the horse's skin,
underneath the other rugs. This has been beneficial in cases that persisted with
lesions in spite of regular laundering of rugs.
Immunotherapy:
Immunotherapy is indicated for horses that are not adequately controlled by allergen
avoidance measures and for those that have pollen reactions, unless they are to
plants with a very narrow pollination season, where symptomatic treatment may be
more appropriate. Allergen selection for formulation of vaccine requires making
judgements about which positive intradermal reactions are clinically significant and
whether or not to include insect extracts in a vaccine. The author's practice is to
recommend allergen avoidance measures in the first instance – both environmental
and insect control – and to consider immunotherapy in those patients where there is
still significant ongoing clinical disease.
Immunomodulatory approaches other than allergen-specific are under active
development, utilising naturally occurring, bacterial-derived, immunomodulators to
down-regulate T-helper 2 and optimise T-helper 1 mechanisms. Extracts under
investigation contain immunomodulators that occur in the bacterial cell wall,
bacterial heat-shock proteins that share homology with mammalian mitochondrialderived
stress proteins and bacterial sugars related to innate immunity and to the
bacteriomimetic sugars presented on the surfaces of rapidly replicating mammalian
cells, such as those of neoplasms and inflammatory responses.
There is in the UK a clinical trial underway, under a VMD test certificate, of a
bacterial-derived product in horses with a clinical diagnosis of
Culicoides hypersensitivity. Two hundred susceptible horses are recruited to the trial,
which is running over this year and into next year, with both open and randomised
elements to the trial. No data will be available until later this year, but in a small
placebo-controlled pilot trial the product has been demonstrated to statistically
significantly reduce the severity of disease. Future results are awaited with interest.
Glucocorticoids:
Severely affected horses, particularly those with marked pruritus and those with
chronic changes related to insect bite hypersensitivity, may well need systemic steroid
therapy. There are often concerns about the risks of steroid therapy in horses, but at
the anti-inflammatory dose rates required for allergic patients the risks are
considered very low, unless there is a history of laminitis.
Prednisolone is the author's drug of choice, given orally at an initial dose rate of 0.5-
1mg/kg/day. Daily therapy used continued until the clinical signs are controlled,
usually within 1-2 weeks, then reduced to alternate day therapy, with gradual tapering
of the dose to the lowest possible maintenance dose as long as is needed. This
ACVSC Proceedings Dermatology Chapter Science Week 2005 51